Page 85 - ICSE Math 5

2 5
Example 16: Add and .
3 6
2 5
Solution: + 3 3, 6
3 6
L.C.M. of 3 and 6 = 3 × 2 = 6 2 1, 2
2 5 1, 1
Convert and to equivalent fractions having the same denominator 6.
3 6
2 5 2 × 2 5 × 1 4 5 4 + 5
+ = + = + = Top Tip
3 6 3 × 2 6 × 1 6 6 6
9 If the sum of fractions
=  Improper fraction is an improper
6
fraction, convert it to
3
= 1 Mixed fraction mixed fraction.
6
2 5 3
So, + = 1 .
3 6 6
11 12
Example 17: Subtract from .
34 17 17 17, 34
12 11
Solution: – 2 1, 2
17 34
L.C.M. of 17 and 34 = 17 × 2 = 34 1, 1
12 11
Convert and to equivalent fractions having the same denominator 34.
17 34
12 11 12 × 2 11 × 1 24 11 24 – 11 13
– = – = – = =
17 34 17 × 2 34 × 1 34 34 34 34
12 11 13
So, – = .
17 34 34
Addition and Subtraction of Whole Numbers and Fractions

Let’s learn to add and subtract a whole number and a fraction.
7 Remember
Example 18: Add 6 and .
9 Every whole number
6 7 6 7
Solution: Since 6 = , so 6 + = + . can be written as a
1 9 1 9 fraction by writing 1 as the
L.C.M. of 1 and 9 = 9 denominator.
6 7 6  9 7  1 54 7 54 + 7 61 7
+ = + = + = = = 6
1 9 1  9 9  1 9 9 9 9 9
7 7
So, 6 + = 6 .
9 9
11
Example 19: Subtract from 4.
13
11 4 11
Solution: 4 – = –
13 1 13
L.C.M. of 1 and 13 = 13
4 11 4  13 11  1 52 11 52 – 11 41 2
– = – = – = = = 3
1 13 1  13 13  1 13 13 13 13 13
11 2
So, 4 – = 3 .
13 13
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